I. Field of the Invention
The present invention relates to a fin retention system for a projectile having deployable fins to hold the fins in their undeployed position until after launch.
II. Description of Related Art
Many projectiles, such as mortars, missiles, and the like, have deployable fins, i.e. fins that are movable between an undeployed position and a deployed position. In their undeployed position, the fins are folded or pivoted towards the projectile thus reducing the overall diameter of the projectile around its fins. Conversely, upon deployment, the fins pivot or fold outwardly to their deployed position thus increasing the overall circumference of the projectile around the fins (i.e., super-caliber fins).
In practice, the fins are maintained in their undeployed position all the way through the launch of the projectile from a launch tube. It is only after the projectile exits from the launch tube that the projectile fins move to their deployed position. Any conventional means, such as springs, or simply the inertia of the fins may be used to move the fins to their deployed position immediately after exiting from the launch tube.
There have been previously known methods and devices to hold the fins in their undeployed position until immediately after launch. For example, there have been previously known active electric or mechanical actuators which move the fins from their undeployed and to their deployed position immediately after launch. These systems, however, are relatively expensive and heavy in construction. Furthermore, since these systems are active systems, the failure of the fin deployment system can occur, possibly with catastrophic results.
Still other systems, such as Kevlar strings and passive bore guides similar to a sabot, have also been previously known to hold the fins in their undeployed position until immediately after launch. These previously known systems have all suffered various disadvantages such as high cost and insufficient reliability.